When does H1B visa Season Start ?
USCIS generally accepts H1B visa
petitions for the next fiscal year on April 1st of the previous year. For instance, USCIS will start accepting H1B visa applications for fiscal year 2012 starting from April 1, 2011. Also, if the H1B petition applied on April 1st gets approved, the person with approved petition can start working from October 1st. For instance, if your H1B petition is applied for FY 2012 on April 1,2011 and it gets approved, then you can start working from October 1st, 2011.
How long does the H1B season Last ?
H1B season ( accepting application for H1B visa ) lasts until the H1B cap is reached. Read H1B visa Cap count for full info.